Light source apparatus and projector

ABSTRACT

A light source apparatus according to an aspect of the present disclosure includes a light source section, a first polarization separator that transmits a first polarization component of first light and reflects a second polarization component of the first light, a second polarization separator that reflects the first polarization component, transmits a third polarization component of second light, and reflects a fourth polarization component of the second light, a diffuser that diffuses the second polarization component and causes the diffused second polarization component, and a wavelength converter that converts the wavelength of the first polarization component and causes the second light. The first polarization separator includes a first polarization separation layer and first bases. The second polarization separator includes a second polarization separation layer and second bases. At least one of the first bases and the second bases is made of quartz.

The present application is based on, and claims priority from JPApplication Serial Number 2019-226353, filed Dec. 16, 2019, thedisclosure of which is hereby incorporated by reference herein in itsentirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a light source apparatus and aprojector.

2. Related Art

There is a known projector that modulates the light outputted from alight source to generate image light based on image information andprojects the generated image light. JP-A-4-60538 discloses aprojection-type color image display apparatus including a light source,a plurality of dichroic mirrors, a liquid crystal display deviceincluding a microlens array, and a projection lens. The projection-typecolor image display apparatus separates white light outputted from thelight source into a plurality of color light fluxes having differentcolors and causes the plurality of separated color light fluxes to beincident on different sub-pixels in one liquid crystal display devicefor color display.

In the projection-type color image display apparatus described above, ared light reflecting dichroic mirror, a green light reflecting dichroicmirror, and a blue light reflecting dichroic mirror are disposed innonparallel to each other along a light incident optical axis of thewhite light outputted from the light source. The white light outputtedfrom the light source passes through the dichroic mirrors describedabove, which separate the white light into red light, green light, andblue light that travel in directions different from one another. The redlight, the green light, and the blue light are incident on redsub-pixels, green sub-pixels, and blue sub-pixels of a light modulatorwith the red light, the green light, and the blue light spatiallyseparated from one another by microlenses provided on the light incidentside of the light modulator.

In the projection-type color image display apparatus disclosed inJP-A-4-60538, a lamp light source, such as a halogen lamp and a xenonlamp, is employed as the white light source, and a liquid crystaldisplay device is employed as the light modulator. The light outputtedfrom the lamp light source is nonpolarized light, and using the liquidcrystal display device as the light modulator requires the lightincident on the liquid crystal display device to be linearly polarizedlight having a specific polarization direction. On the other hand, as anilluminator that uniformly illuminates the liquid crystal displaydevice, it is conceivable that a pair of multi-lens arrays that dividelight incident thereon into a plurality of sub-light fluxes and apolarization converter that aligns the polarization directions of theplurality of sub-light fluxes with one another are provided between thewhite light source and the liquid crystal display device. In this case,a frequently used polarization converter includes a plurality ofpolarization separation layers and a plurality of reflection layersalternately arranged along a direction that intersects the lightincident direction and phase retardation layers provided in the opticalpath of the light having passed through the polarization separationlayers or the optical path of the light reflected off the reflectionlayers.

When the size of the projection-type color image display apparatusdescribed above is reduced to meet the need of size reduction in recentyears, however, it is difficult to manufacture a polarization converterhaving a small interval between the polarization separation layers andthe reflection layers. It is therefore difficult to reduce the size of alight source apparatus including a polarization converter of this typeand in turn the size of a projector including the light sourceapparatus. In view of the problems described above, it is desired toprovide a light source apparatus capable of outputting a plurality ofcolor light fluxes having an aligned polarization direction withoutusing a small-interval polarization converter.

SUMMARY

To achieve the object described above, a light source apparatusaccording to an aspect of the present disclosure includes a light sourcesection that outputs first light that belongs to a first wavelengthband, a first polarization separator that transmits in a first directiona first polarization component of the first light incident from thelight source section along the first direction and reflects a secondpolarization component of the first light in a second direction thatintersects the first direction, a second polarization separator that isdisposed in a position shifted in the first direction from the firstpolarization separator, reflects in the second direction the firstpolarization component incident from the first polarization separatoralong the first direction, transmits a third polarization component ofsecond light that belongs to a second wavelength band different from thefirst wavelength band in a third direction that is opposite the seconddirection, and reflects a fourth polarization component of the secondlight in a fourth direction that is opposite the first direction, adiffuser that is disposed in a position shifted in the second directionfrom the first polarization separator, diffuses the second polarizationcomponent incident from the first polarization separator along thesecond direction, and causes the diffused second polarization componentto exit in the third direction, and a wavelength converter that isdisposed in a position shifted in the second direction from the secondpolarization separator, converts a wavelength of the first polarizationcomponent incident from the second polarization separator along thesecond direction, and causes the second light to exit in the thirddirection. The first polarization separator includes a firstpolarization separation layer and first bases so provided as to sandwichthe first polarization separation layer. The second polarizationseparator includes a second polarization separation layer and secondbases so provided as to sandwich the second polarization separationlayer. At least one of the first bases and the second bases is made ofquartz.

A light source apparatus according to another aspect of the presentdisclosure includes a light source section that outputs first light thatbelongs to a first wavelength band, a first polarization separator thattransmits in a first direction a first polarization component of thefirst light incident from the light source section along the firstdirection and reflects a second polarization component of the firstlight in a second direction that intersects the first direction, asecond polarization separator that is disposed in a position shifted inthe first direction from the first polarization separator, reflects inthe second direction the first polarization component incident from thefirst polarization separator along the first direction, transmits athird polarization component of second light that belongs to a secondwavelength band different from the first wavelength band in a thirddirection that is opposite the second direction, and reflects a fourthpolarization component of the second light in a fourth direction that isopposite the first direction, a diffuser that is disposed in a positionshifted in the second direction from the first polarization separator,diffuses the second polarization component incident from the firstpolarization separator along the second direction, and causes thediffused second polarization component to exit in the third direction,and a wavelength converter that is disposed in a position shifted in thesecond direction from the second polarization separator, converts awavelength of the first polarization component incident from the secondpolarization separator along the second direction, and causes the secondlight to exit in the third direction. The first polarization separatorincludes a first polarization separation layer and first bases soprovided as to sandwich the first polarization separation layer. Thesecond polarization separator includes a second polarization separationlayer and second bases so provided as to sandwich the secondpolarization separation layer. At least one of the first bases and thesecond bases is made of a material that absorbs light that belongs tothe first wavelength band at a light absorption factor smaller than orequal to 0.1% per length t=10 mm, where t represents an optical pathlength of light in the first bases and the second bases.

A light source apparatus according to another aspect of the presentdisclosure includes a light source section that outputs first light thatbelongs to a first wavelength band, a first polarization separator thattransmits in a first direction a first polarization component of thefirst light incident from the light source section along the firstdirection and reflects a second polarization component of the firstlight in a second direction that intersects the first direction, asecond polarization separator that is disposed in a position shifted inthe first direction from the first polarization separator, reflects inthe second direction the first polarization component incident from thefirst polarization separator along the first direction, transmits athird polarization component of second light that belongs to a secondwavelength band different from the first wavelength band in a thirddirection that is opposite the second direction, and reflects a fourthpolarization component of the second light in a fourth direction that isopposite the first direction, a diffuser that is disposed in a positionshifted in the second direction from the first polarization separator,diffuses the second polarization component incident from the firstpolarization separator along the second direction, and causes thediffused second polarization component to exit in the third direction,and a wavelength converter that is disposed in a position shifted in thesecond direction from the second polarization separator, converts awavelength of the first polarization component incident from the secondpolarization separator along the second direction, and causes the secondlight to exit in the third direction. The first polarization separatorincludes a first polarization separation layer and first bases soprovided as to sandwich the first polarization separation layer. Thesecond polarization separator includes a second polarization separationlayer and second bases so provided as to sandwich the secondpolarization separation layer. At least one of the first bases and thesecond bases is made of a material having a photoelastic constantsmaller than or equal to 0.1 nm/cm/10⁵ Pa.

The light source apparatus according to any of the aspects of thepresent disclosure may further include a first phase retarder which isprovided between the first polarization separator and the diffuser andon which the second polarization component is incident from the firstpolarization separator.

The light source apparatus according to any of the aspects of thepresent disclosure may further include a second phase retarder thatconverts the third polarization component that exits out of the secondpolarization separator in the third direction into the fourthpolarization component.

In the light source apparatus according to any of the aspects of thepresent disclosure, the light source section may include a lightemitting device and a third phase retarder on which light outputted fromthe light emitting device is incident and which outputs the first lightcontaining the first polarization component and the second polarizationcomponent.

In the light source apparatus according to one of the aspects of thepresent disclosure, the third phase retarder may be rotatable around anaxis of rotation along a traveling direction of light incident on thethird phase retarder.

The light source apparatus according to any of the aspects of thepresent disclosure may further include a first color separator that isdisposed in a position shifted in the third direction from the firstpolarization separator and separates light that exits out of the firstpolarization separator into third light that belongs to the firstwavelength band and fourth light that belongs to the second wavelengthband and a second color separator that is disposed in a position shiftedin the third direction from the second polarization separator andseparates light that exits out of the second polarization separator intofifth light that belongs to a third wavelength band different from thesecond wavelength band and sixth light that belongs to a fourthwavelength band different from the second wavelength band and the thirdwavelength band.

A projector according to another aspect of the present disclosureinclude the light source apparatus according one of the aspects of thepresent disclosure, a light modulator that modulates light from thelight source apparatus in accordance with image information, and aprojection optical apparatus that projects the light modulated by thelight modulator.

The projector according to the aspect of the present disclosure mayfurther include a homogenizer provided between the light sourceapparatus and the light modulator, and the homogenizer may include twomulti-lenses that divide the light incident from the light sourceapparatus into a plurality of sub-light fluxes and a superimposing lensthat superimposes the plurality of sub-light fluxes incident from thetwo multi-lenses on one another on the light modulator.

In the projector according to the aspect of the present disclosure, thelight modulator may include a liquid crystal panel having a plurality ofpixels and a microlens array provided on a light incident side of theliquid crystal panel and including a plurality of microlensescorresponding to the plurality of pixels. The plurality of pixels mayeach have a first sub-pixel, a second sub-pixel, a third sub-pixel, anda fourth sub-pixel. The microlenses may cause the third light to beincident on the first sub-pixels, the fourth light to be incident on thesecond sub-pixels, the fifth light to be incident on the thirdsub-pixels, and the sixth light to be incident on the fourth sub-pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a projector according toa first embodiment.

FIG. 2 is a perspective view of a light source apparatus according tothe first embodiment.

FIG. 3 is a plan view of the light source apparatus viewed from thepositive side of a direction Y.

FIG. 4 is a side view of the light source apparatus viewed from thenegative side of a direction X.

FIG. 5 is a side view of the light source apparatus viewed from thepositive side of the direction X.

FIG. 6 is a diagrammatic view showing light incident positions on amulti-lens that are the positions where color light fluxes are incidenton the multi-lens.

FIG. 7 is an enlarged view of a light modulator.

FIG. 8 is a plan view of a light source apparatus according toComparative Example viewed from the positive side of the direction Y.

FIG. 9 is a side view of a light source apparatus according to a secondembodiment viewed from the negative side of the direction X.

FIG. 10 is a diagrammatic view showing light incident positions on amulti-lens that are the positions where color light fluxes are incidenton the multi-lens.

DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment

A first embodiment of the present disclosure will be described belowwith reference to FIGS. 1 to 8.

FIG. 1 is a schematic configuration diagram of a projector 1 accordingto the present embodiment.

In the following drawings, components are drawn at different dimensionalscales in some cases for clarity of each of the components.

The projector 1 according to the present embodiment modulates lightoutputted from a light source apparatus 2 to form an image according toimage information and enlarges and projects the formed image on aprojection receiving surface, such as a screen. In other words, theprojector 1 causes a light modulator 6 including one liquid crystalpanel 61 to modulate the light outputted from the light source apparatus2 to form an image and projects the formed image. The projector 1 iswhat is called a single-panel projector.

The projector 1 includes the light source apparatus 2, a homogenizer 4,a field lens 5, the light modulator 6, and a projection opticalapparatus 7, as shown in FIG. 1. The light source apparatus 2, thehomogenizer 4, the field lens 5, the light modulator 6, and theprojection optical apparatus 7 are disposed in predetermined positionsalong an illumination optical axis Ax. The illumination optical axis Axis defined as an axis along the traveling direction of the chief ray oflight L outputted from the light source apparatus 2.

The configurations of the light source apparatus 2 and the homogenizer 4will be described later in detail.

The field lens 5 is disposed between the homogenizer 4 and the lightmodulator 6. The field lens 5 parallelizes the light L having exited outof the homogenizer 4 and guides the parallelized light L to the lightmodulator 6.

The projection optical apparatus 7 projects the light modulated by thelight modulator 6, that is, image forming light on a projectionreceiving surface (not shown), such as a screen. The projection opticalapparatus 7 includes one or more projection lenses.

In the following description, an axis parallel to the travelingdirection of the light outputted from the light source apparatus 2 alongthe illumination optical axis Ax is called an axis Z, and the travelingdirection of the light is called a direction +Z. Two axes perpendicularto the axis Z and perpendicular to each other are called axes X and Y.Out of the directions along the axes described above, the upwarddirection of the vertical direction in the space where the projector 1is installed is called a direction +Y. The rightward direction of thehorizontal direction when a target object on which the light is incidentalong the direction +Z is so viewed that the direction +Y is orientedupward in the vertical direction is called a direction +X. Although notshown, the direction opposite the direction +X is called a direction −X,the direction opposite the direction +Y is called a direction −Y, andthe direction opposite the direction +Z is called a direction −Z.

The direction +X in the present embodiment corresponds to the firstdirection in the appended claims, and the direction −Z in the presentembodiment corresponds to the second direction in the appended claims.The direction +Z in the present embodiment corresponds to the thirddirection in the appended claims, and the direction −X in the presentembodiment corresponds to the second direction in the appended claims.

Configuration of Light Source Apparatus

FIG. 2 is a perspective view of the light source apparatus 2 accordingto the present embodiment. FIG. 3 is a plan view of the light sourceapparatus 2 viewed from the direction +Y.

The light source apparatus 2 outputs the light L, with which the lightmodulator 6 is illuminated, in the direction parallel to theillumination optical axis Ax, that is, in the direction +Z, as shown inFIGS. 2 and 3. The light L outputted by the light source apparatus 2 islinearly polarized light having an aligned polarization direction andcontains a plurality of spatially separate color light fluxes. In thepresent embodiment, the light L outputted by the light source apparatus2 is formed of four light fluxes each formed of S-polarized light. Thefour light fluxes are formed of blue light BLs, yellow light YLs, greenlight GLs, and red light RLs.

The light source apparatus 2 includes a light source section 21, a firstpolarization separator 22, a second polarization separator 23, a firstphase retarder 24, a first light collector 25, a diffusion apparatus 26,a second light collector 27, a wavelength converter 28, a first colorseparator 29, a fourth phase retarder 30, a reflector 31, a second phaseretarder 32, and a second color separator 33.

A P-polarization component in the present embodiment corresponds to thefirst polarization component in the appended claims, and anS-polarization component in the present embodiment corresponds to thesecond polarization component in the appended claims. Further, the firstpolarization separator 22 and the second polarization separator 23differ from the first color separator 29 and the second color separator33 in terms of the orientation of films that separate the polarizationcomponents or the color light fluxes from each other. Therefore, theP-polarization component and the S-polarization component are expressedby the polarization direction with respect to the first polarizationseparator 22 and the second polarization separator 23 and are reversedfor the polarization direction with respect to the first color separator29 and the second color separator 33. That is, the P-polarizationcomponent with respect to the first polarization separator 22 and thesecond polarization separator 23 is the S-polarization component withrespect to the first color separator 29 and the second color separator33, and the S-polarization component with respect to the firstpolarization separator 22 and the second polarization separator 23 isthe P-polarization component with respect to the first color separator29 and the second color separator 33. It is, however, noted that theP-polarization component and the S-polarization component arehereinafter expressed for the polarization direction with respect to thefirst polarization separator 22 and the second polarization separator 23to avoid confused description.

Configuration of Light Source Section

The light source section 21 outputs blue light BLs, which enters thefirst polarization separator 22, along the direction +X. The lightsource section 21 includes a plurality of light emitters 211, aplurality of collimator lenses 212, and a rotary phase retardationapparatus 213. The light emitters 211 are each formed of a solid-statelight source that outputs the blue light BLs. Specifically, the lightemitters 211 are each formed of a semiconductor laser that outputsS-polarized blue light BLs. The blue light BLs is laser light thatbelongs to a blue wavelength band, for example, from 440 to 480 nm andhas a peak wavelength that falls within, for example, a range from 450to 460 nm. That is, the light source section 21 outputs the blue lightBLs that belongs to the blue wavelength band. In the present embodiment,the plurality of light emitters 211 are arranged along the axis Z. Thelight source section 21 in the present embodiment includes two lightemitters 211, but the number of light emitters 211 is not limited to aspecific number and may be one. The arrangement of the plurality oflight emitters 211 is also not limited to a specific arrangement. Thelight emitters 211 are so disposed as to output the blue light BLsformed of the S-polarized component and may instead be so disposed as tooutput blue light formed of the P-polarized component because the rotaryphase retardation apparatus 213 can arbitrarily set the ratio betweenthe amount of S-polarized light and the amount of P-polarized light.That is, the light emitters 211 may be rotated by 90° around the opticalaxis of the outputted light.

The blue light BLs that belongs to the blue wavelength band in thepresent embodiment corresponds to the first light that belongs to afirst wavelength band in the appended claims.

The plurality of collimator lenses 212 are provided between theplurality of light emitters 211 and the rotary phase retardationapparatus 213. The collimator lenses 212 are each provided incorrespondence with one of the light emitters 211. The collimator lenses212 parallelize the light L outputted from the light emitters 211.

The rotary phase retardation apparatus 213 includes a third phaseretarder 2131 and a rotator 2132. The third phase retarder 2131 isrotatable around an axis of rotation along the traveling direction ofthe light incident on the third phase retarder 2131, that is, an axis ofrotation parallel to the axis X. The rotator 2132 is formed, forexample, of a motor and rotates the third phase retarder 2131.

The third phase retarder 2131 is formed of a half wave plate or aquarter wave plate. Part of the blue light BLs formed of the S-polarizedcomponent having entered the third phase retarder 2131 is converted bythe third phase retarder 2131 into blue light BLp formed of theP-polarized component. The blue light having passed through the thirdphase retarder 2131 is therefore the mixture of the blue light BLsformed of the S-polarized component and the blue light BLp formed of theP-polarized component mixed at a predetermined ratio. That is, the thirdphase retarder 2131 receives the blue light BLs outputted from the lightemitters 211 and outputs the blue light containing the S-polarizedcomponent and the P-polarized component.

The rotator 2132 adjusts the angle of rotation of the third phaseretarder 2131 to adjust the ratio between the amount of blue light BLsformed of the S-polarized component and the amount of blue light BLpformed of the P-polarized component contained in the light that passesthrough the third phase retarder 2131. The rotator 2132, which rotatesthe third phase retarder 2131, may not be provided when no adjustment ofthe ratio between the amount of blue light BLs and the amount of bluelight BLp is necessary. In this case, the angle of rotation of the thirdphase retarder 2131 is so set that the ratio between the amount of bluelight BLs and the amount of blue light BLp is a preset ratio, and theangle of rotation of the third phase retarder 2131 is then fixed.

The light source section 21 thus outputs the light containing the bluelight BLs formed of the S-polarized component and the blue light BLpformed of the P-polarized component. In the present embodiment, theplurality of light emitters 211 are each configured to output the bluelight BLs formed of the S-polarized component, and a light emitter 211that outputs the blue light BLs formed of the S-polarized component anda light emitter 211 that outputs the blue light BLp formed of theP-polarized component may be mixed with each other. According to theconfiguration described above, the rotary phase retardation apparatus213 can be omitted. Further, the light emitters 211 are not necessarilyeach formed of a semiconductor laser and may each be formed of anothersolid-state light source, such as an LED (light emitting diode).

Configuration of First Polarization Separator

The light containing the blue light BLs formed of the S-polarizedcomponent and the blue light BLp formed of the P-polarized componententers the first polarization separator 22 along the direction +X. Thefirst polarization separator 22 is formed of a prism-shaped polarizationseparator. The first polarization separator 22 includes a firstpolarization separation layer 221 and two first bases 222, which are soprovided as to sandwich the first polarization separation layer 221.Specifically, the two first bases 222 each have the shape of asubstantially right-angled isosceles triangular column. The two firstbases 222 are combined with each other with the inclining surfacesthereof facing each other into a substantially box-like shape as awhole. The first polarization separation layer 221 is provided betweenthe inclining surfaces of the two first bases 222. The firstpolarization separation layer 221 therefore inclines by 45° with respectto the axes X and Z. In other words, the first polarization separationlayer 221 inclines by 45° with respect to the planes XY and YZ.

The first polarization separation layer 221 has a polarizationseparation characteristic that causes the first polarization separationlayer 221 to transmit the P-polarized component of the incident lightand reflect the S-polarized component of the incident light. The firstpolarization separation layer 221 further has a wavelength selectivepolarization separation characteristic that causes the firstpolarization separation layer 221 to transmit P-polarized light andreflect S-polarized light of light that belongs to the blue wavelengthband and reflect light having wavelengths longer than those in the bluewavelength band irrespective of the polarization sate of the incidentlight. The first polarization separator 22 therefore transmits along thedirection +X the blue light BLp formed of the P-polarized component outof the blue light incident on the first polarization separator 22 alongthe direction +X and reflects along the direction −Z the blue light BLsformed of the S-polarized component out of the incident blue light. Thefirst polarization separation layer 221 is formed, for example, of adielectric multilayer film.

In the present embodiment, the first bases 222 are made of quartz.Quartz absorbs light that belongs to the blue wavelength band at a lightabsorption factor of about 0.01% per length t=10 mm, where t representsthe optical path length of the light in the first bases 222. That is,quartz is a material having a light absorption factor smaller than orequal to 0.1. Quartz is broadly classified into fused quartz produced byfusing natural crystallized quartz powder and synthetic quartz thathardly contains metal impurities and is chemically synthesized. In thepresent embodiment, synthetic quartz is desirably used.

The first bases 222 are instead made of a material having a photoelasticconstant smaller than or equal to 0.1 nm/cm/10⁵ Pa. As an example of aspecific material of the first bases 222, PBH56 (product name,manufactured by OHARA Inc.), which is one type of optical glass, can beused. PBH56 is a low-photoelastic optical glass material having arefractive index nd of 1.84139 and a photoelastic constant of 0.09nm/cm/10⁵ Pa.

Configuration of Second Polarization Separator

The second polarization separator 23 is disposed in a position shiftedin the direction +X from the first polarization separator 22. The bluelight BLp formed of the P-polarized component having passed through thefirst polarization separator 22 enters the second polarization separator23. The second polarization separator 23 is formed of a prism-shapedpolarization separator, as the first polarization separator 22 is. Thesecond polarization separator 23 includes a second polarizationseparation layer 231 and two second bases 232, which are so provided asto sandwich the second polarization separation layer 231.

Specifically, the two second bases 232 each have the shape of asubstantially right-angled isosceles triangular column. The two secondbases 232 are combined with each other with the inclining surfacesthereof facing each other into a substantially box-like shape as awhole. The second polarization separation layer 231 is provided betweenthe inclining surfaces of the two second bases 232. The secondpolarization separation layer 231 therefore inclines by 45° with respectto the axes X and Z. In other words, the second polarization separationlayer 231 inclines by 45° with respect to the planes XY and YZ. Thesecond polarization separation layer 231 is disposed in parallel to thefirst polarization separation layer 221.

The second polarization separation layer 231 has a wavelength selectivepolarization separation characteristic that causes the secondpolarization separation layer 231 to reflect blue light, reflect theS-polarized light out of light having wavelengths longer than those inthe blue wavelength band, and transmit P-polarized light out of thelight. The second polarization separator 23 therefore reflects in thedirection −Z the blue light BLp formed of the P-polarized componentincident from the first polarization separator 22. The secondpolarization separation layer 231 is formed, for example, of adielectric multilayer film.

In the present embodiment, the second bases 232 are made of quartz,which is a material that absorbs light that belongs to the bluewavelength band at the light absorption factor smaller than or equal to0.1% per length t=10 mm, as the first bases 222 are. Synthetic quartz isdesirably used as the quartz. The second bases 232 are instead made of alow-photoelastic optical glass material having a photoelastic constantsmaller than or equal to 0.1 nm/cm/10⁵ Pa, such as PBH56 describedabove.

In the present embodiment, the first polarization separator 22 and thesecond polarization separator 23 are configured to be separate members.The first polarization separator 22 and the second polarizationseparator 23 are therefore bonded to each other, although not shown, viaa bonding material provided between surfaces of the polarizationseparators that are the surfaces facing each other. The firstpolarization separator 22 and the second polarization separator 23 mayinstead be integrated with each other. That is, the first base 222adjacent to the second polarization separator 23 and the second base 232adjacent to the first polarization separator 22 may be a common membermade of a single material.

In the present embodiment, the first bases 222 and the second bases 232are both made of quartz. In place of the configuration described above,one of the first bases 222 and the second bases 232 may be made ofquartz that is a material that absorbs light that belongs to the bluewavelength band at the light absorption factor smaller than or equal to0.1% per length t=10 mm. Instead, one of the first bases 222 and thesecond bases 232 may be made of a material having a photoelasticconstant smaller than or equal to 0.1 nm/cm/10⁵ Pa.

Configuration of First Phase Retarder

The first phase retarder 24 is located in a position shifted in thedirection −Z from the first polarization separator 22. That is, thefirst phase retarder 24 is disposed between the first polarizationseparator 22 and the diffusion apparatus 26 along the axis Z. The firstphase retarder 24 is formed of a quarter wave plate for the wavelengthof the blue light BLs and the blue light BLp incident thereon. The bluelight BLs formed of the S-polarized component reflected off the firstpolarization separator 22 is converted by the first phase retarder 24,for example, into right-handed circularly polarized blue light BLc1,which then exits toward the first light collector 25. That is, the firstphase retarder 24 converts the polarization state of the blue light BLsincident thereon.

Configuration of First Light Collector

The first light collector 25 is disposed in a position shifted in thedirection −Z from the first phase retarder 24. That is, the first lightcollector 25 is disposed between the first phase retarder 24 and thediffusion apparatus 26 along the axis Z. The first light collector 25collects the blue light BLc1 incident from the first phase retarder 24into a spot on a diffusion plate 261 of the diffusion apparatus 26.Further, the first light collector 25 parallelizes blue light Blc2,which will be described later and is incident from the diffusionapparatus 26. In the example shown in FIG. 2, the first light collector25 is formed of a first lens 251 and a second lens 252, but the numberof lenses that form the first light collector 25 is not limited to aspecific number.

Configuration of Diffusion Apparatus

The diffusion apparatus 26 is disposed in a position shifted in thedirection −Z from the first light collector 25. That is, the diffusionapparatus 26 is disposed in a position shifted in the direction −Z fromthe first polarization separator 22. The diffusion apparatus 26diffusively reflects in the direction +Z the blue light BLc1 incident inthe direction −Z from the first light collector 25 at the same angle ofdiffusion as that of yellow light YL emitted from the wavelengthconverter 28, which will be described later. The diffusion apparatus 26includes the diffusion plate 261 and a rotator 262. The diffusion plate261 preferably has a reflection characteristic as close as possible tothe Lambert scattering characteristic and reflects the blue light BLc1incident on the reflection plate 261 over a wide angular range. Therotator 262 is formed, for example, of a motor and rotates the diffusionplate 261 around an axis of rotation Rx parallel to the direction +Z.

The diffusion plate 261 in the present embodiment corresponds to thediffuser in the appended claims.

The blue light BLc1 incident on the diffusion plate 261 is converted,when reflected off the diffusion plate 261, into the blue light BLc2,which is circularly polarized light having a polarization rotationdirection opposite the polarization rotation direction of the incidentblue light BLc1. That is, the right-handed circularly polarized bluelight BLc1 is converted by the diffusion plate 261 into the left-handedcircularly polarized blue light BLc2. The blue light Blc2 outputted fromthe diffusion apparatus 26 passes in the direction +Z through the firstlight collector 25 and then enters the first phase retarder 24 again. Inthis process, the blue light BLc2 that enters the first phase retarder24 via the first light collector 25 is converted by the first phaseretarder 24 into the blue light BLp formed of the P-polarized component.The converted blue light BLp passes through the first polarizationseparator 22 in the direction +Z and enters the first color separator29.

Configuration of Second Light Collector

The second light collector 27 is disposed in a position shifted in thedirection −Z from the second polarization separator 23. That is, thesecond light collector 27 is disposed between the second polarizationseparator 23 and the wavelength converter 28 along the axis Z. Thesecond light collector 27 collects the blue light BLp reflected off thesecond polarization separator 23 into a spot on the wavelength converter28. Further, the second light collector 27 parallelizes the yellow lightYL, which is emitted from the wavelength converter 28 and will bedescribed later, and causes the parallelized yellow light YL to exittoward the second polarization separator 23. In the example shown inFIG. 2, the second light collector 27 is formed of a first lens 271 anda second lens 272, but the number of lenses that form the second lightcollector 27 is not limited to a specific number.

Configuration of Wavelength Converter

The wavelength converter 28 is disposed in a position shifted in thedirection −Z from the second light collector 27. That is, the wavelengthconverter 28 is disposed in a position shifted in the direction −Z fromthe second polarization separator 23. The wavelength converter 28 is areflective wavelength converter that is excited with light incidentthereon and emits light having a wavelength different from thewavelength of the incident light in the direction opposite the lightincident direction. In other words, the wavelength converter 28 convertsthe wavelength of the incident light and emits the light converted interms of wavelength in the direction opposite the light incidentdirection.

In the present embodiment, the wavelength converter 28 contains a yellowphosphor that emits yellow light when excited with blue light.Specifically, the wavelength converter 28 contains, for example, anyttrium-aluminum-garnet-based (YAG-based) phosphor containing cerium(Ce) as the activator. The wavelength converter 28 emits in thedirection +Z fluorescence that belongs to a yellow wavelength bandformed of wavelengths longer than those in the blue wavelength band towhich the blue light BLp, which is incident along the direction −Z,belongs, that is, the nonpolarized yellow light YL. The yellow light YLbelongs, for example, to a wavelength band from 500 to 700 nm. Theyellow light YL contains a green light component and a red lightcomponent that are each a mixture of the S-polarized component and theP-polarized component.

The fluorescence that belongs to the yellow wavelength band in thepresent embodiment, that is, the nonpolarized yellow light YLcorresponds to the second light that belongs to a second wavelength bandin the appended claims.

The yellow light YL emitted from the wavelength converter 28 passesalong the direction +Z through the second light collector 27, whichparallelizes the yellow light YL, and the parallelized yellow light YLthen enters the second polarization separator 23. The wavelengthconverter 28 in the present embodiment is an immobile wavelengthconverter. In place of the configuration described above, the wavelengthconverter 28 may be a rotary wavelength converter including a rotatorthat rotates the wavelength converter 28 around an axis of rotationparallel to the axis Z. In this case, an increase in temperature of thewavelength converter 28 is suppressed, whereby the wavelength conversionefficiency of the wavelength converter 28 can be increased.

The second polarization separation layer 231 of the second polarizationseparator 23 has the wavelength selective polarization separationcharacteristic for light that belongs to the yellow wavelength band, asdescribed above. Therefore, out of the nonpolarized yellow light YLincident on the second polarization separation layer 231, the yellowlight YLs formed of the S-polarized component is reflected off thesecond polarization separation layer 231 in the direction −X and entersthe first polarization separator 22. The first polarization separationlayer 221 of the first polarization separator 22 is so characterized asto reflect the yellow light YLs irrespective of the polarization statethereof, as described above. The yellow light YLs incident on the firstpolarization separation layer 221 along the direction −X is thereforereflected off the first polarization separator 22 in the direction +Zand enters the first color separator 29.

On the other hand, out of the nonpolarized yellow light YL incident onthe second polarization separation layer 231, yellow light YLp formed ofthe P-polarized component passes through the second polarizationseparation layer 231 in the direction +Z, exits out of the secondpolarization separator 23, and enters the second phase retarder 32.

The yellow light YLp formed of the P-polarized component in the presentembodiment corresponds to the third polarization component in theappended claims, and the yellow light YLs formed of the S-polarizedcomponent in the present embodiment corresponds to the fourthpolarization component in the appended claims.

Configuration of First Color Separator

FIG. 4 is a side view of the light source apparatus 2 viewed from thedirection −X. That is, FIG. 4 shows the first color separator 29, thefourth phase retarder 30, the reflector 31, and other components viewedfrom the direction −X. In FIG. 4, the rotary phase retardation apparatus213, the first phase retarder 24, the first light collector 25, thediffusion apparatus 26, and other components are omitted for ease ofillustration.

The first color separator 29 is disposed in a position shifted in thedirection +Z from the first polarization separator 22, as shown in FIG.4. The first color separator 29 includes a dichroic prism 291 and thereflection prism 292. The dichroic prism 291 and the reflection prism292 are disposed side by side along the axis Y. The first colorseparator 29 separates the light having exited in the direction +Z outof the first polarization separator 22 into the blue light BLp and theyellow light YLs.

The light containing the blue light BLp and the yellow light YLs havingexited out of the first polarization separator 22 enters the dichroicprism 291. The dichroic prism 291 is formed of a prism-shaped colorseparator formed by combining two bases each being a substantiallyright-angled isosceles triangular column with each other into asubstantially box-like shape. A color separation layer 2911 is providedat the interface between the two bases. The color separation layer 2911inclines by 45° with respect to the axes Y and Z. In other words, thecolor separation layer 2911 inclines by 45° with respect to the planesXY and YZ.

The color separation layer 2911 functions as a dichroic mirror thattransmits blue light out of the incident light and reflects color lighthaving wavelengths longer than those in the blue wavelength band, thatis, yellow light out of the incident light. Therefore, out of the lighthaving entered the dichroic prism 291 from the first polarizationseparator 22, the blue light BLp passes through the color separationlayer 2911 in the direction +Z and exits out of the dichroic prism 291.

On the other hand, out of the light having entered the dichroic prism291 from the first polarization separator 22, the yellow light YLs isreflected off the color separation layer 2911 in the direction −Y. Thedichroic prism 291 may be replaced with a dichroic mirror including thecolor separation layer 2911. The first color separator 29 may insteadinclude a polarization separator having a polarization separation layerand the reflection prism 292. Even when the dichroic prism 291 isreplaced, for example, with as the first color separator 29 apolarization separator that transmits the incident blue light BLp in thedirection +Z and reflects the yellow light YLs in the direction −Ytoward the reflection prism 292, the polarization separator can separatethe blue light BLp and the yellow light YLs from each other, as thefirst color separator 29 including the dichroic prism 291 can.

The reflection prism 292 is disposed in a position shifted in thedirection −Y from the dichroic prism 291. The yellow light YLs reflectedoff the color separation layer 2911 enters the reflection prims 292. Thereflection prism 292 is a prism-shaped reflector formed by combining twobases each being a substantially right-angled isosceles triangularcolumn with each other into a substantially box-like shape. A reflectionlayer 2921 is provided at the interface between the two bases. Thereflection layer 2921 inclines by 45° with respect to the directions +Yand +Z. In other words, the reflection layer 2921 inclines by 45° withrespect to the planes XY and YZ. That is, the reflection layer 2921 isdisposed in parallel to the color separation layer 2911.

The reflection layer 2921 reflects in the direction +Z the yellow lightYLs incident from the dichroic prism 291 in the direction −Y. The yellowlight YLs reflected off the reflection layer 2921 exits in the direction+Z out of the reflection prism 292. The reflection prism 292 may bereplaced with a reflection mirror including the reflection layer 2921.

Configuration of Fourth Phase Retarder

The fourth phase retarder 30 is disposed in a position shifted in thedirection +Z from the dichroic prism 291. In other words, the fourthphase retarder 30 is disposed in the optical path of the blue light BLphaving exited out of the dichroic prism 291. The fourth phase retarder30 is formed of a half wave plate for the blue wavelength band to whichthe blue light BLp incident thereon belongs. The fourth phase retarder30 converts the blue light BLp incident from the dichroic prism 291 intothe blue light BLs formed of the S-polarized component. The convertedblue light BLs formed of the S-polarized component from the fourth phaseretarder 30 exits out of the light source apparatus 2 in the direction+Z and enters the homogenizer 4 shown in FIG. 1. The fourth phaseretarder 30 may be so provided as to be in contact with a surface of thedichroic prism 291 that is the surface via which the blue light BLpexits.

Configuration of Reflector

The reflector 31 is disposed in a position shifted in the direction +Zfrom the reflection prism 292. In other words, the reflector 31 isdisposed in the optical path of the yellow light YLs having exited outof the reflection prism 292. The reflector 31 is formed of ahalf-silvered mirror that transmits part of the light incident thereonand reflects the remainder. It is, however, noted that the transmittanceand reflectance provided by the half-silvered mirror may be arbitrarilyset in accordance with the white balance of the light L outputted fromthe light source apparatus 2. For example, the transmittance is set at80%, and the reflectance is set at 20′.

Therefore, out of the yellow light YLs incident on the reflector 31,part of the yellow light YLs passes through the reflector 31 and exitsout of the light source apparatus 2 in the direction +Z and enters thehomogenizer 4. That is, the yellow light YLs is spatially separated fromthe blue light BLs, exits via a light exiting position on the lightsource apparatus 2 that is the position different from the light exitingposition via which the blue light BLs exits, and enters the homogenizer4. In detail, the yellow light YLs exits via the light exiting positionseparate in the direction −Y from the light exiting position on thelight source apparatus 2 that is the position via which the blue lightBLs exits, and the yellow light YLs then enters the homogenizer 4.

On the other hand, the remainder of the yellow light YLs incident on thereflector 31 is reflected off the reflector 31 and enters the reflectionprism 292 again. The remainder of the yellow light YLs having enteredthe reflection prism 292 is reflected off the reflection layer 2921 inthe direction +Y and incident on the wavelength converter 28 via thedichroic prism 291, the first polarization separator 22, the secondpolarization separator 23, and the second light collector 27.

The yellow phosphor contained in the wavelength converter 28 hardlyabsorbs yellow light externally incident thereon. The yellow light YLsincident on the wavelength converter 28 is therefore not absorbed in thewavelength converter 28 but is repeatedly reflected or scattered in thewavelength converter 28 to form the nonpolarized yellow light YL. Thenonpolarized yellow light YL exits out of the wavelength converter 28again along with the yellow light YL newly generated in the yellowphosphor. The yellow light YL emitted from the wavelength converter 28then enters the second polarization separator 23 via the second lightcollector 27, as described above. The ratio between the amount of yellowlight YLs passing through the reflector 31 and the amount of yellowlight YLs reflected off the reflector 31 can be set in advance, asdescribed above. The reflector 31 may be so provided as to be in contactwith a surface of the reflection prism 292 that is the surface via whichthe yellow light YLs exits.

Configuration of Second Phase Retarder

FIG. 5 is a side view of the light source apparatus 2 viewed from thedirection +X. In other words, FIG. 5 shows the second phase retarder 32and the second color separator 33 viewed from the direction +X. In FIG.5, the second light collector 27 and the wavelength converter 28 areomitted.

The second phase retarder 32 is disposed in a position shifted in thedirection +Z from the second polarization separator 23, as shown inFIGS. 3 and 5. The yellow light YLP having passed through the secondpolarization separator 23 enters the second phase retarder 32. Thesecond phase retarder 32 is formed of a half wave plate for the yellowwavelength band to which the yellow light YLp belongs. The second phaseretarder 32 converts the yellow light YLp formed of the P-polarizedcomponent into the yellow light YLs formed of the S-polarized component.The converted yellow light YLs formed of the S-polarized componententers the second color separator 33.

Configuration of Second Color Separator

The second color separator 33 is disposed in a position shifted in thedirection +Z from the second phase retarder 32, as shown in FIG. 5. Thatis, the second color separator 33 is disposed in a position shifted inthe direction +Z from the second polarization separator 23. The secondcolor separator 33 includes a dichroic prism 331 and a reflection prism332. The dichroic prism 331 and the reflection prism 332 are disposedside by side along the axis Y. The second color separator 33 separatesthe yellow light YLs having exited out of the second polarizationseparator 23 in the direction +Z and having been converted by the secondphase retarder 32 into the S-polarized component into the green lightGLs and the red light RLs.

The dichroic prism 331 is formed of a prism-shaped color separator, asthe dichroic prism 291 is. A color separation layer 3311 is provided atthe interface between the two bases. The color separation layer 3311inclines by 45° with respect to the directions +Y and +Z. In otherwords, the color separation layer 3311 inclines by 45° with respect tothe planes XY and YZ. The color separation layer 3311 is disposed inparallel to the reflection layer 3321.

The color separation layer 3311 functions as a dichroic mirror thattransmits in the direction +Z the green light component out of theincident light and reflects in the direction −Y the red light componentout of the incident light. Therefore, out of the yellow light YLs havingentered the dichroic prism 331, the S-polarized green light GLs passesthrough the color separation layer 3311 in the direction +Z and exitsout of the dichroic prism 331. The S-polarized green light GLs exits outof the light source apparatus 2 in the direction +Z and enters thehomogenizer 4. That is, the green light GLs is spatially separated fromthe blue light BLs and the yellow light YLs and exits via a positiondifferent from the positions via which the blue light BLs and the yellowlight YLs exit and enters the homogenizer 4. In other words, the greenlight GLs exits via a light exiting position on the light sourceapparatus 2 that is a position separate in the direction +X from thelight exiting position via which the blue light BLs exits, and the greenlight GLs then enters the homogenizer 4.

On the other hand, out of the yellow light YLs having entered thedichroic prism 331, the red light RLs formed of the S-polarizedcomponent is reflected off the color separation layer 3311 in thedirection −Y. The dichroic prism 331 may be replaced with a dichroicmirror including the color separation layer 3311.

The reflection prism 332 has the same configuration as that of thereflection prism 292. That is, the reflection prism 332 includes areflection layer 3321 parallel to the color separation layers 2911 and3311 and the reflection layer 2921.

The reflection layer 3321 reflects in the direction +Z the red light RLsreflected off the color separation layer 3311 and incident on thereflection layer 3321. The red light RLs reflected off the reflectionlayer 3321 exits out of the reflection prism 332. The red light RLs isoutputted from the light source apparatus 2 in the direction +Z andenters the homogenizer 4. That is, the red light RLs is spatiallyseparated from the blue light BLs, the yellow light YLs, and the greenlight GLs and exits via a position different from the positions viawhich the blue light BLs, the yellow light YLs, and the green light GLsexit and enters the homogenizer 4. In other words, the red light RLsexits via a light exiting position on the light source apparatus 2 thatis a position separate in the direction −Y from the light exitingposition via which the green light GLs exits and separate in thedirection +X from the light exiting position via which the yellow lightYLs exits, and the red light RLs then enters the homogenizer 4.

Configuration of Homogenizer

The homogenizer 4 homogenizes the illuminance in an image formation areaof the light modulator 6 irradiated with the light outputted from thelight source apparatus 2, as shown in FIG. 1. The homogenizer 4 includesa first multi-lens 41, a second multi-lens 42, and a superimposing lens43.

The first multi-lens 41 includes a plurality of lenses 411 arranged in amatrix in a plane perpendicular to the center axis of the light Lincident from the light source apparatus 2, that is, the illuminationaxis Ax. The plurality of lenses 411 of the first multi-lens 41 dividethe light incident from the light source apparatus 2 into a plurality ofsub-light fluxes.

FIG. 6 is a diagrammatic view showing the light incident positions onthe first multi-lens 41 viewed from the direction −Z that are thepositions where the color light fluxes are incident on the firstmulti-lens 41.

The blue light BLs, the yellow light YLs, the green light GLs, and thered light RLs outputted from the light source apparatus 2 enter thefirst multi-lens 41, as shown in FIG. 6. The blue light BLs outputtedvia a position on the light source apparatus 2 that is a positionshifted in the direction −X and the direction +Y enter a plurality oflenses 411 present in an area A1 of the first multi-lens 41 that is anarea shifted in the direction −X and the direction +Y. The yellow lightYLs outputted via a position on the light source apparatus 2 that is aposition shifted in the direction −X and the direction −Y enter aplurality of lenses 411 present in an area A2 of the first multi-lens 41that is an area shifted in the direction −X and the direction −Y.

The green light GLs outputted via a position on the light sourceapparatus 2 that is a position shifted in the direction +X and thedirection +Y enter a plurality of lenses 411 present in an area A3 ofthe first multi-lens 41 that is an area shifted in the direction +X andthe direction +Y. The red light RLs outputted via a position on thelight source apparatus 2 that is a position shifted in the direction +Xand the direction −Y enter a plurality of lenses 411 present in an areaA4 of the first multi-lens 41 that is an area shifted in the direction+X and the direction −Y. The color light fluxes having entered thelenses 411 form a plurality of sub-light fluxes, which enter the lenses421 of the second multi-lens 42 that correspond to the lenses 411.

Out of the light L outputted from the light source apparatus 2 accordingto the present embodiment, the blue light BLs corresponds to the thirdlight in the appended claims, the yellow light YLs corresponds to thefourth light in the appended claim, the green light GLs corresponds tothe fifth light in the appended claim, and the red light RLs correspondsto the sixth light in the appended claim.

The second multi-lens 42 includes a plurality of lenses 421, which arearranged in a matrix in a plane perpendicular to the illuminationoptical axis Ax and correspond to the plurality of lenses 411 of thefirst multi-lens 41, as shown in FIG. 1. The plurality of sub-lightfluxes having exited out of the lenses 411 corresponding to the lenses421 enter the lenses 421. The lenses 421 cause the sub-light fluxesincident thereon to enter the superimposing lens 43.

The superimposing lens 43 superimposes the plurality of sub-light fluxesincident from the second multi-lens 42 on one another in the imageformation area of the light modulator 6. In detail, the secondmulti-lens 42 and the superimposing lens 43 cause the blue light BLs,the yellow light YLs, the green light GLs, and the red light RLs eachdivided into the plurality of sub-light fluxes to enter a plurality ofmicrolenses 621, which form a microlens array 62, which will bedescribed later, of the light modulator 6 via the field lens 5 atdifferent angles of incidence.

Configuration of Light Modulator

The light modulator 6 modulates the light outputted from the lightsource apparatus 2, as shown in FIG. 1. In detail, the light modulator 6modulates the color light fluxes outputted from the light sourceapparatus 2 and incident on the light modulator 6 via the homogenizer 4and the field lens 5 in accordance with image information to form imagelight according to the image information. The light modulator 6 includesone liquid crystal panel 61 and one microlens array 62.

Configuration of Liquid Crystal Panel

FIG. 7 is a diagrammatic view that is an enlarged view of part of thelight modulator 6 viewed from the direction −Z. In other words, FIG. 7shows the correspondence between pixels PX provided in the liquidcrystal panel 61 and the microlenses 621 provided in the microlens array62.

The liquid crystal panel 61 has a plurality of pixels PX arranged in amatrix in a plane perpendicular to the illumination optical axis Ax, asshown in FIG. 7.

The pixels PX each have a plurality of sub-pixels SX, which modulatecolor light fluxes having colors different from one another. In thepresent embodiment, the pixels PX each have four sub-pixels SX (SX1 toSX4). Specifically, in one pixel PX, the first sub-pixel SX1 is disposedin a position shifted in the direction −X and the direction +Y. Thesecond sub-pixel SX2 is disposed in a position shifted in the direction−X and the direction −Y. The third sub-pixel SX3 is disposed in aposition shifted in the direction +X and the direction +Y. The fourthsub-pixel SX4 is disposed in a position shifted in the direction +X andthe direction −Y.

Configuration of Microlens Array

The microlens array 62 is provided on a side of the liquid crystal panel61 that is the direction −Z, which is the light incident side, as shownin FIG. 1. The microlens array 62 guides the color light fluxes thatenter the microlens array 62 to the individual pixels PX. The microlensarray 62 includes a plurality of microlenses 621 corresponding to theplurality of pixels PX.

The plurality of microlenses 621 are arranged in a matrix in a planeperpendicular to the illumination optical axis Ax. In other words, theplurality of microlenses 621 are arranged in a matrix in a planeperpendicular to the center axis of the light incident via the fieldlens 5. In the present embodiment, the microlenses 621 are each providedin correspondence with two sub-pixels arranged in the direction +X andtwo sub-pixels arranged in the direction +Y. That is, the microlenses621 are each provided in correspondence with the four sub-pixels SX1 toSX4 in the form of a matrix formed of two rows and two columns in theplane XY.

The blue light BLs, the yellow light YLs, the green light GLs, and thered light RLs superimposed by the homogenizer 4 on one another enter themicrolenses 621 at different angles of incidence. The microlenses 621cause each of the color light fluxes incident thereon to be incident onthe sub-pixels SX corresponding to the color light flux. Specifically,the microlenses 621 each cause, out of the sub-pixels SX of thecorresponding pixel PX, the blue light BLs to be incident on the firstsub-pixel SX1, the yellow light YLs to be incident on the secondsub-pixel SX2, the green light GLs to be incident on the third sub-pixelSX3, and the red light RLs to be incident on the fourth sub-pixel SX4.The color light fluxes are thus incident on the sub-pixels SX1 to SX4corresponding to the color light fluxes, and the sub-pixels SX1 to SX4modulate the corresponding color light fluxes. The image light thusmodulated by the liquid crystal panel 61 is projected by the projectionoptical apparatus 7 on the projection receiving surface that is notshown.

Effects of First Embodiment

In the projector of related art described in JP-A-4-60538, a lamp isused as the light source. Since the light outputted from the lamp haspolarization directions that are not aligned with one another, apolarization conversion section for aligning the polarization directionswith one another is required to use a liquid crystal panel as the lightmodulator. The projector typically uses a polarization conversionsection including a multi-lens array and a polarization separator (PBS)array. To reduce the size of the projector, however, a multi-lens arrayand a PBS array each having a small interval are required, but it isvery difficult to produce a PBS array having a small interval.

To solve the problem described above, in the present embodiment, thelight source apparatus 2 outputs four color light fluxes having analigned polarization direction, that is, the blue light BLs formed ofthe S-polarized component, the yellow light YLs formed of theS-polarized component, the green light GLs formed of the S-polarizedcomponent, and the red light RLs formed of the S-polarized component.According to the configuration described above, a light source apparatus2 capable of outputting a plurality of color light fluxes that arespatially separated from one another and have an aligned polarizationdirection can be achieved without use of a polarization converter havinga small interval, such as that described above. The size of the lightsource apparatus 2 and in turn the size of the projector 1 can thus bereduced.

Further, in the projector 1 according to the present embodiment, theyellow light YLs enters the light modulator 6 in addition to the bluelight BLs, the green light GLs, and the red light RLs, whereby theluminance of an image projected from the projection optical apparatus 7can be increased.

In the present embodiment, the light source section 21 includes thethird phase retarder 2131, whereby the blue light BLp formed of theP-polarized component and the blue light BLs formed of the S-polarizedcomponent are reliably allowed to enter the first polarization separator22. Further, according to the configuration described above, since thelight fluxes outputted from the plurality of light emitting devices 211may have the same polarization direction, solid-state light sources ofthe same type may be disposed in the same orientation, whereby theconfiguration of the light source section 21 can be simplified.

In the present embodiment, since the third phase retarder 2131 isrotatable around an axis of rotation along the direction +X, adjustmentof the angle of rotation of the third phase retarder 2131 allowsadjustment of the ratio between the amount of blue light BLs and theamount of blue light BLp that enter the first polarization separator 22.The ratio between the amount of blue light BLs outputted from the lightsource apparatus 2 and the amounts of yellow light YLs, the green lightGLs, and the red light RLs also outputted from the light sourceapparatus 2 can thus be adjusted, whereby the white balance of the lightfrom the light source apparatus 2 can be adjusted.

In the present embodiment, the first phase retarder 24 is providedbetween the first polarization separator 22 and the first lightcollector 25, whereby the circularly polarized blue light BLc2 outputtedfrom the diffusion apparatus 26 can be converted into the blue light BLpformed of the P-polarized component, which can pass through the firstpolarization separation layer 221 of the first polarization separator22. The blue light BLc2 outputted from the diffusion apparatus 26 canthus be used with increased efficiency.

In the present embodiment, the second phase retarder 32 is providedbetween the second polarization separator 23 and the second colorseparator 33, whereby the yellow light YLp formed of the P-polarizedcomponent that exits out of the second polarization separator 23 can beconverted into the yellow light YLs formed of the S-polarized component.The green light GLs and the red light RLs having exited out of thesecond color separator 33 can therefore each be light formed of theS-polarized component, whereby the blue light BLs, the yellow light YLs,the green light GLs, and the red light RLs outputted from the lightsource apparatus 2 can each be light formed of the S-polarizedcomponent.

In the present embodiment, the reflector 31, which reflects part of theyellow light YLs, is provided on the light exiting side of the firstcolor separator 29 that is the side via which the yellow light YLsexits, whereby the ratio between the amount of yellow light YLsoutputted from the light source apparatus 2 and the amounts of greenlight GLs and the red light RLs also outputted from the light sourceapparatus 2 can be adjusted. The white balance of the light from thelight source apparatus 2 can thus be adjusted. Further, the luminance ofa projection image can be increased by increasing the ratio of theamount of yellow light YLs to the amounts of other color light fluxes.Moreover, the color reproducibility of a projection image can beincreased by increasing the ratio of the amounts of green light GLs andred light RLs to the amounts of other color light fluxes.

In the present embodiment, the light source apparatus 2 includes thefirst light collector 25, which collects the blue light BLs into a spoton the diffusion apparatus 26, whereby the first light collector 25 canefficiently collect the blue light BLs having exited out of the firstphase retarder 24 into a spot on the diffusion apparatus 26 andparallelize the blue light BLs outputted from the diffusion apparatus26. As a result, loss of the blue light BLs can be suppressed, wherebythe blue light BLs can be used at increased efficiency.

In the present embodiment, the light source apparatus 2 includes thesecond light collector 27, which collects the blue light BLp into a spoton the wavelength converter 28, whereby the second light collector 27can efficiently collect the blue light BLp having exited out of thesecond polarization separator 23 into a spot on the wavelength converter28 and parallelize the yellow light YL emitted from the wavelengthconverter 28. As a result, loss of the blue light BLp and the yellowlight YL can be suppressed, whereby the blue light BLs and the yellowlight YL can be used at increased efficiency.

Consider now a light source apparatus according to Comparative Examplebelow.

FIG. 8 is a plan view of a light source apparatus 102 according toComparative Example viewed from the direction +Y. In FIG. 8, componentscommon to those of the light source apparatus 2 according to the presentembodiment have the same reference characters. Further, in FIG. 8, thefirst color separator 29, the second color separator 33, and othercomponents are omitted.

In the light source apparatus 102 according to Comparative Example,first bases 124, of which a first polarization separator 122 is formed,are made of typical optical glass, such as borosilicate glass, arepresentative example of which is, for example, BK7, unlike the basesin the present embodiment, as shown in FIG. 8. Similarly, second bases125, of which a second polarization separator 123 is formed, are made oftypical optical glass, such as borosilicate glass, unlike the bases inthe present embodiment. The other configurations of the light sourceapparatus 102 are the same as those of the light source apparatus 2according to the present embodiment.

When the first polarization separator 122 and the second polarizationseparator 123 are irradiated with the light from the light sourcesection 21, heat is generated in the first polarization separator 122and the second polarization separator 123. In the case where the firstbases 124, of which the first polarization separator 122 is formed, andthe second bases 125, of which the second polarization separator 123 isformed, are made of typical optical glass, such as borosilicate glass,the first bases 124 and the second bases 125 are thermally distorted,and birefringence resulting from the thermal distortion occurs. As aresult, the polarization state of the light traveling through the firstpolarization separator 122 and the second polarization separator 123 isdisturbed.

Specifically, part of the blue light BLp formed of the P-polarizedcomponent that exits out of the first phase retarder 24, enters thefirst polarization separator 122, and then travels toward the firstpolarization separation layer 221 is changed to blue light BLs2 formedof the S-polarized component. The blue light BLs2 is then reflected offthe first polarization separation layer 221 in the direction −X. Part ofthe yellow light YLs reflected off the second polarization separationlayer 231 and then traveling toward the first polarization separationlayer 221 is changed to yellow light YLp2 formed of the P-polarizedcomponent. The yellow light YLp2 then passes through the firstpolarization separation layer 221 in the direction −X.

The blue light BLs2 and the yellow light YLp2 form light that returnsfrom the first polarization separator 122 to the light source section21, resulting in optical loss. As described above, the light sourceapparatus 102 according to Comparative Example causes loss of the bluelight and the yellow light, possibly resulting in a decrease in thelight use efficiency.

To solve the problem described above, in the light source apparatus 2according to the present embodiment, the first bases 222 and the secondbases 232 are made of quartz. Quartz absorbs light that belongs to theblue wavelength band at the light absorbance factor of about 0.01% perlength t=10 mm, which is sufficiently smaller than the light absorbancefactor of typical optical glass. The first bases 222 or the second bases232 are therefore hardly thermally distorted, so that birefringencehardly occurs. When the first bases 222 and the second bases 232 aremade of a material having a photoelastic constant smaller than or equalto 0.1 nm/cm/10⁵ Pa, the first bases 222 and the second bases 232 arethermally distorted, unlike in the case of quartz, but birefringencehardly occurs even when thermal distortion occurs.

Therefore, even when the first bases 222 and the second bases 232 aremade of either of the materials described above, the blue light BLpformed of the P-polarized component that exits out of the first phaseretarder 24, enters the first polarization separator 122, and thentravels toward the first polarization separation layer 221 substantiallyentirely passes through the first polarization separation layer 221 inthe direction +Z. Further, the yellow light YLs formed of theS-polarized component that is reflected off the second polarizationseparation layer 231 and then travels toward the first polarizationseparation layer 221 is substantially entirely reflected off the firstpolarization separation layer 221 in the direction +Z. As describedabove, the light source apparatus 2 according to the present embodimentcan use the blue light BLp and the yellow light YLs at increased lightuse efficiency with almost no loss of the blue light BLp and the yellowlight YLs, as compared with the light source apparatus 102 according toComparative Example.

Quartz, PBH56, and other similar materials exemplified in the presentembodiment are more expensive than typical optical glass. However, sincethe light source apparatus and the projector according to the presentembodiment are each compact, the first polarization separator 22 and thesecond polarization separator 23 are each also compact, whereby anincrease in manufacturing cost can be minimized.

In the present embodiment, in which the projector 1 includes thehomogenizer 4 located between the light source apparatus 2 and the lightmodulator 6, the light modulator 6 can be substantially uniformlyilluminated with the blue light BLs, the yellow light YLs, the greenlight GLs, and the red light RLs outputted from the light sourceapparatus 2. Color unevenness and luminance unevenness in a projectionimage can thus be suppressed.

In the present embodiment, in which the light modulator 6 includes themicrolens array 62 including a plurality of microlenses 621corresponding to the plurality of pixels PX, the microlenses 621 eachallow the four color light fluxes that enter the light modulator 6 to beincident on the corresponding four sub-pixels SX of the liquid crystalpanel 61. The color light fluxes outputted from the light sourceapparatus 2 can thus be efficiently incident on the sub-pixels SX,whereby the color light fluxes can be used at increased efficiency.

Second Embodiment

A second embodiment of the present disclosure will be described belowwith reference to FIGS. 9 and 10.

The basic configuration of the light source apparatus according to thesecond embodiment is the same as that in the first embodiment, and theconfiguration of the reflector differs from that in the firstembodiment. The entire light source apparatus will therefore not bedescribed.

FIG. 9 is a side view of the light source apparatus according to thesecond embodiment viewed from the direction −X. FIG. 10 is adiagrammatic view showing the light incident positions on a multi-lensthat are the positions where the color light fluxes are incident on themulti-lens. In FIG. 9, the rotary phase retardation apparatus 213, thefirst phase retarder 24, the first light collector 25, and the diffusionapparatus 26 are omitted.

In FIGS. 9 and 10, components common to those in the figures used in thefirst embodiment have the same reference characters and will not bedescribed.

A light source apparatus 20 according to the present embodiment includesa third color separator 35 in place of the reflector 31 in the lightsource apparatus 2 according to the first embodiment, as shown in FIG.9. That is, the third color separator 35 is disposed in a positionshifted in the direction +Z from the reflection prism 292 in the opticalpath of the yellow light YLs separated by the first color separator 29.The third color separator 35 is formed of a dichroic mirror socharacterized as to transmit the green light GLs and reflect the redlight RLs.

Green light GLs2, which is contained in the yellow light YLs incidentfrom the reflection prism 292 of the first color separator 29 on thethird color separator 35, passes through the third color separator 35and exits out of the light source apparatus 20. That is, the lightsource apparatus 20 outputs the green light GLs2 in place of the yellowlight YLs via a position on the light source apparatus 2 according tothe first embodiment that is the position via which the yellow light YLsexits.

Therefore, in the present embodiment, the green light GLs2 that exitsvia the position via which the yellow light YLs exits in the lightsource apparatus 2 corresponds to the fourth light in the appendedclaims.

On the other hand, the red light RLs, which is contained in the yellowlight YLs incident on the third color separator 35, is reflected off thethird color separator 35 and enters the reflection prism 292 from thedirection +Z. The red light RLs enters the wavelength converter 28 viathe first color separator 29, the first polarization separator 22, thesecond polarization separator 23, and the second light collector 27, asthe yellow light YLs reflected off the reflector 31 in the light sourceapparatus 2 according to the first embodiment does.

The yellow phosphor contained in the wavelength converter 28 hardlyabsorbs yellow light externally incident thereon, as described above,and the yellow phosphor therefore also hardly absorbs the red light RLs.The red light RLs incident on the wavelength converter 28 is thereforerepeatedly reflected in the wavelength converter 28 to form nonpolarizedred light, which exits out of the wavelength converter 28 along with theyellow light YL generated by the yellow phosphor. Out of the red lightemitted from the wavelength converter 28, the red light RLs formed ofthe S-polarized component is reflected off the third color separator 35and returns to the wavelength converter 28 again, and the red lightformed of the P-polarized component passes through the secondpolarization separator 23 in the direction +Z and exits out of the lightsource apparatus 20. The third color separator 35 may instead be adichroic prism.

The light source apparatus 20 outputs the blue light BLs, the greenlight GLs2, the green light GLs, and the red light RLs, as shown in FIG.10. The green light GLs2 exits via a position on the light sourceapparatus 20 that is a position shifted in the direction −X and thedirection −Y and enters the plurality of lenses 411 disposed in the areaA2 of the first multi-lens 41 that is an area shifted in the direction−X and the direction −Y. Although not shown, the green light GLs2 entersthe microlenses 621 via the first multi-lens 41, the second multi-lens42, the superimposing lens 43, and the field lens 5, as the yellow lightYLs in the first embodiment does. The green light GLs having enteredeach the microlenses 621 is incident on the second sub-pixel SX2 in thepixel PX corresponding to the microlens 621.

Effects of Second Embodiment

The present embodiment also provides the same effects as those providedby the first embodiment, for example, a light source apparatus 20capable of outputting a plurality of color light fluxes having analigned polarization direction can be achieved without use of apolarization converter having a small interval, and the sizes of thelight source apparatus 20 and the projector 1 can be reduced.

Further, the light source apparatus 20 according to the secondembodiment outputs the green light GLs2 in place of the yellow light YLsin the light source apparatus 2 according to the first embodiment,whereby the amount of green light GLs incident on the pixels PX can beincreased. The visibility of a projection image can thus be increased.

The third color separator 35 may instead be a dichroic mirror socharacterized as to reflect the green light GLs and transmit the redlight RLs, in contrast to the present embodiment. Depending on theyellow phosphor contained in the wavelength converter 28, the red lightcontained in the yellow light YL emitted from the wavelength converter28 is insufficient in some cases. In such cases, using the dichroicmirror characterized as described above allows the red light to beincident on the second sub-pixels SX2 and the fourth sub-pixels SX4 outof the four sub-pixels SX1 to SX4. The color reproducibility of aprojection image can thus be increased.

The technical range of the present disclosure is not limited to theembodiments described above, and a variety of changes can be made to theembodiments to the extent that the changes do not depart from thesubstance of the present disclosure.

For example, in the embodiments described above, the position via whichthe yellow light YLs exits out of the first color separator 29 is aposition shifted in the direction −Y from the position via which theblue light BLs exits, and the position via which the red light RLs exitsout of the second color separator 33 is a position shifted in thedirection −Y from the position via which the green light GLs exits. Inplace of the arrangement described above, the position via which theyellow light YLs exits out of the first color separator 29 may be aposition shifted in the direction +Y from the position via which theblue light BLs exits, and the position via which the red light RLs exitsout of the second color separator 33 may be a position shifted in thedirection +Y from the position via which the green light GLs exits.

In the embodiments described above, the P-polarized componentcorresponds to the first polarization component, and the S-polarizedcomponent corresponds to the second polarization component.Specifically, the first polarization separator 22 transmits the bluelight BLp formed of the P-polarized component, which is the firstpolarization component, and reflects the blue light BLs formed of theS-polarized component, which is the second polarization component. Thesecond polarization separator 23 reflects the blue light BLp formed ofthe P-polarized component, which is the first polarization component,transmits the yellow light YLp formed of the P-polarized component,which is the first polarization component, and reflects the yellow lightYLs formed of the S-polarized component, which is the secondpolarization component. The configurations described above are notnecessarily employed. The S-polarized component may be the firstpolarization component, and the P-polarized component may be the secondpolarization component. In this case, for example, the firstpolarization separator 22 may reflect the blue light BLp formed of theP-polarized component, which is the second polarization component,transmit the blue light BLs formed of the S-polarized component, whichis the first polarization component, and reflect the yellow light YLsformed of the S-polarized component, which is the second polarizationcomponent. The second polarization separator 23 may reflect the bluelight BLs formed of the S-polarized component, which is the firstpolarization component, reflect the yellow light YLs formed of theS-polarized component, which is the first polarization component, andtransmit the yellow light YLp formed of the P-polarized component, whichis the second polarization component. That is, the second polarizationseparator 23 may be a polarization separator that reflects light formedof the S-polarized component, which is the first polarization component,and transmits light formed of the P-polarized component, which is thesecond polarization component.

The light source apparatus 2 according to the first embodiment and thelight source apparatus 20 according to the second embodiment eachinclude the first light collector 25 and the second light collector 27,but not necessarily. At least one of the first light collector 25 andthe second light collector 27 may not be provided.

In the embodiments described above, the light source section 21 outputsthe blue light BLs and the blue light BLp in the direction +X, but notnecessarily. The light source section 21 may output the blue light BLsand the blue light BLp in a direction that intersects the direction +X,cause the blue light BLs and the blue light BLp to be reflected off, forexample, a reflection member, and cause the blue light BLs and the bluelight BLp to travel in the direction +X and enter the first polarizationseparator 22.

In the embodiments described above, the projector includes thehomogenizer 4 including the first multi-lens 41, the second multi-lens42, and the superimposing lens 43. In place of the configurationdescribed above, a homogenizer 4 having another configuration may beprovided, or no homogenizer 4 may be provided.

The light source apparatus 2 according to the first embodiment describedabove and the light source apparatus 20 according to the secondembodiment described above output the color light fluxes via four lightexiting positions, and the liquid crystal panel 61, which forms thelight modulator 6, has four sub-pixels SX in each of the pixels PX. Inplace of the configuration described above, the light source apparatusesmay each output three color light fluxes, and the liquid crystal panelmay have three sub-pixels in each of the pixels. In this case, forexample, in the light source apparatus according to each of theembodiments described above, a total reflection member may be providedin the optical path of the yellow light YLs.

The light source apparatus 2 according to the first embodiment outputsthe blue light BLs, the yellow light YLs, the green light GLs, and thered light RLs, which are each S-polarized light and are spatiallyseparated from one another. The light source apparatus 20 according tothe second embodiment outputs the blue light BLs, the green light GLs,and the red light RLs, which are each S-polarized light and arespatially separated from one another. In place of the configurationsdescribed above, the color light fluxes outputted by each of the lightsource apparatuses may each have another polarization state. Forexample, the light source apparatuses may each be configured to output aplurality of color light fluxes that are each P-polarized light and arespatially separated from one another. The color light fluxes outputtedby each of the light source apparatuses are not limited to blue light,yellow light, green light, and red light and may be other color lightfluxes. For example, the light source apparatuses may each be configuredto output white light in place of the blue light and the yellow light.

In addition to the above, the shape, the number, the arrangement, thematerial, and other factors of each component of the light sourceapparatus and the projector are not limited to those in the embodimentsdescribed above and can be changed as appropriate. Further, the aboveembodiments have been described with reference to the case where thelight source apparatuses according to the present disclosure are eachincorporated in a projector, but not necessarily. The light sourceapparatus according to each aspect of the present disclosure may be usedas a lighting apparatus, a headlight of an automobile, and othercomponents.

What is claimed is:
 1. A light source apparatus comprising: a lightsource section that outputs first light that belongs to a firstwavelength band; a first polarization separator that transmits in afirst direction a first polarization component of the first lightincident from the light source section along the first direction andreflects a second polarization component of the first light in a seconddirection that intersects the first direction; a second polarizationseparator that is disposed in a position shifted in the first directionfrom the first polarization separator, reflects in the second directionthe first polarization component incident from the first polarizationseparator along the first direction, transmits a third polarizationcomponent of second light that belongs to a second wavelength banddifferent from the first wavelength band in a third direction that isopposite the second direction, and reflects a fourth polarizationcomponent of the second light in a fourth direction that is opposite thefirst direction; a diffuser that is disposed in a position shifted inthe second direction from the first polarization separator, diffuses thesecond polarization component incident from the first polarizationseparator along the second direction, and causes the diffused secondpolarization component to exit in the third direction; and a wavelengthconverter that is disposed in a position shifted in the second directionfrom the second polarization separator, converts a wavelength of thefirst polarization component incident from the second polarizationseparator along the second direction, and causes the second light toexit in the third direction, wherein the first polarization separatorincludes a first polarization separation layer and first bases soprovided as to sandwich the first polarization separation layer, thesecond polarization separator includes a second polarization separationlayer and second bases so provided as to sandwich the secondpolarization separation layer, and at least one of the first bases andthe second bases is made of quartz.
 2. A light source apparatuscomprising: a light source section that outputs first light that belongsto a first wavelength band; a first polarization separator thattransmits in a first direction a first polarization component of thefirst light incident from the light source section along the firstdirection and reflects a second polarization component of the firstlight in a second direction that intersects the first direction; asecond polarization separator that is disposed in a position shifted inthe first direction from the first polarization separator, reflects inthe second direction the first polarization component incident from thefirst polarization separator along the first direction, transmits athird polarization component of second light that belongs to a secondwavelength band different from the first wavelength band in a thirddirection that is opposite the second direction, and reflects a fourthpolarization component of the second light in a fourth direction that isopposite the first direction; a diffuser that is disposed in a positionshifted in the second direction from the first polarization separator,diffuses the second polarization component incident from the firstpolarization separator along the second direction, and causes thediffused second polarization component to exit in the third direction;and a wavelength converter that is disposed in a position shifted in thesecond direction from the second polarization separator, converts awavelength of the first polarization component incident from the secondpolarization separator along the second direction, and causes the secondlight to exit in the third direction, wherein the first polarizationseparator includes a first polarization separation layer and first basesso provided as to sandwich the first polarization separation layer, thesecond polarization separator includes a second polarization separationlayer and second bases so provided as to sandwich the secondpolarization separation layer, and at least one of the first bases andthe second bases is made of a material that absorbs light that belongsto the first wavelength band at a light absorption factor smaller thanor equal to 0.1% per length t=10 mm, where t represents an optical pathlength of light in the first bases and the second bases.
 3. A lightsource apparatus comprising: a light source section that outputs firstlight that belongs to a first wavelength band; a first polarizationseparator that transmits in a first direction a first polarizationcomponent of the first light incident from the light source sectionalong the first direction and reflects a second polarization componentof the first light in a second direction that intersects the firstdirection; a second polarization separator that is disposed in aposition shifted in the first direction from the first polarizationseparator, reflects in the second direction the first polarizationcomponent incident from the first polarization separator along the firstdirection, transmits a third polarization component of second light thatbelongs to a second wavelength band different from the first wavelengthband in a third direction that is opposite the second direction, andreflects a fourth polarization component of the second light in a fourthdirection that is opposite the first direction; a diffuser that isdisposed in a position shifted in the second direction from the firstpolarization separator, diffuses the second polarization componentincident from the first polarization separator along the seconddirection, and causes the diffused second polarization component to exitin the third direction; and a wavelength converter that is disposed in aposition shifted in the second direction from the second polarizationseparator, converts a wavelength of the first polarization componentincident from the second polarization separator along the seconddirection, and causes the second light to exit in the third direction,wherein the first polarization separator includes a first polarizationseparation layer and first bases so provided as to sandwich the firstpolarization separation layer, the second polarization separatorincludes a second polarization separation layer and second bases soprovided as to sandwich the second polarization separation layer, and atleast one of the first bases and the second bases is made of a materialhaving a photoelastic constant smaller than or equal to 0.1 nm/cm/10⁵Pa.
 4. The light source apparatus according to claim 1, furthercomprising a first phase retarder which is provided between the firstpolarization separator and the diffuser and on which the secondpolarization component is incident from the first polarizationseparator.
 5. The light source apparatus according to claim 1, furthercomprising a second phase retarder that converts the third polarizationcomponent that exits out of the second polarization separator in thethird direction into the fourth polarization component.
 6. The lightsource apparatus according to claim 1, wherein the light source sectionincludes a light emitting device and a third phase retarder on whichlight outputted from the light emitting device is incident and whichoutputs the first light containing the first polarization component andthe second polarization component.
 7. The light source apparatusaccording to claim 6, wherein the third phase retarder is rotatablearound an axis of rotation along a traveling direction of light incidenton the third phase retarder.
 8. The light source apparatus according toclaim 1, further comprising: a first color separator that is disposed ina position shifted in the third direction from the first polarizationseparator and separates light that exits out of the first polarizationseparator into third light that belongs to the first wavelength band andfourth light that belongs to the second wavelength band; and a secondcolor separator that is disposed in a position shifted in the thirddirection from the second polarization separator and separates lightthat exits out of the second polarization separator into fifth lightthat belongs to a third wavelength band different from the secondwavelength band and sixth light that belongs to a fourth wavelength banddifferent from the second wavelength band and the third wavelength band.9. A projector comprising: the light source apparatus according to claim8; a light modulator that modulates light from the light sourceapparatus in accordance with image information; and a projection opticalapparatus that projects the light modulated by the light modulator. 10.The projector according to claim 9, further comprising a homogenizerprovided between the light source apparatus and the light modulator,wherein the homogenizer includes two multi-lenses that divide the lightincident from the light source apparatus into a plurality of sub-lightfluxes, and a superimposing lens that superimposes the plurality ofsub-light fluxes incident from the two multi-lenses on one another onthe light modulator.
 11. The projector according to claim 10, whereinthe light modulator includes a liquid crystal panel having a pluralityof pixels and a microlens array provided on a light incident side of theliquid crystal panel and including a plurality of microlensescorresponding to the plurality of pixels, the plurality of pixels eachhave a first sub-pixel, a second sub-pixel, a third sub-pixel, and afourth sub-pixel, and the microlenses cause the third light to beincident on the first sub-pixels, the fourth light to be incident on thesecond sub-pixels, the fifth light to be incident on the thirdsub-pixels, and the sixth light to be incident on the fourth sub-pixels.12. The light source apparatus according to claim 2, further comprising:a first color separator that is disposed in a position shifted in thethird direction from the first polarization separator and separateslight that exits out of the first polarization separator into thirdlight that belongs to the first wavelength band and fourth light thatbelongs to the second wavelength band; and a second color separator thatis disposed in a position shifted in the third direction from the secondpolarization separator and separates light that exits out of the secondpolarization separator into fifth light that belongs to a thirdwavelength band different from the second wavelength band and sixthlight that belongs to a fourth wavelength band different from the secondwavelength band and the third wavelength band.
 13. A projectorcomprising: the light source apparatus according to claim 12; a lightmodulator that modulates light from the light source apparatus inaccordance with image information; and a projection optical apparatusthat projects the light modulated by the light modulator.
 14. Theprojector according to claim 13, further comprising a homogenizerprovided between the light source apparatus and the light modulator,wherein the homogenizer includes two multi-lenses that divide the lightincident from the light source apparatus into a plurality of sub-lightfluxes, and a superimposing lens that superimposes the plurality ofsub-light fluxes incident from the two multi-lenses on one another onthe light modulator.
 15. The projector according to claim 14, whereinthe light modulator includes a liquid crystal panel having a pluralityof pixels and a microlens array provided on a light incident side of theliquid crystal panel and including a plurality of microlensescorresponding to the plurality of pixels, the plurality of pixels eachhave a first sub-pixel, a second sub-pixel, a third sub-pixel, and afourth sub-pixel, and the microlenses cause the third light to beincident on the first sub-pixels, the fourth light to be incident on thesecond sub-pixels, the fifth light to be incident on the thirdsub-pixels, and the sixth light to be incident on the fourth sub-pixels.16. The light source apparatus according to claim 3, further comprising:a first color separator that is disposed in a position shifted in thethird direction from the first polarization separator and separateslight that exits out of the first polarization separator into thirdlight that belongs to the first wavelength band and fourth light thatbelongs to the second wavelength band; and a second color separator thatis disposed in a position shifted in the third direction from the secondpolarization separator and separates light that exits out of the secondpolarization separator into fifth light that belongs to a thirdwavelength band different from the second wavelength band and sixthlight that belongs to a fourth wavelength band different from the secondwavelength band and the third wavelength band.
 17. A projectorcomprising: the light source apparatus according to claim 16; a lightmodulator that modulates light from the light source apparatus inaccordance with image information; and a projection optical apparatusthat projects the light modulated by the light modulator.
 18. Theprojector according to claim 17, further comprising a homogenizerprovided between the light source apparatus and the light modulator,wherein the homogenizer includes two multi-lenses that divide the lightincident from the light source apparatus into a plurality of sub-lightfluxes, and a superimposing lens that superimposes the plurality ofsub-light fluxes incident from the two multi-lenses on one another onthe light modulator.
 19. The projector according to claim 18, whereinthe light modulator includes a liquid crystal panel having a pluralityof pixels and a microlens array provided on a light incident side of theliquid crystal panel and including a plurality of microlensescorresponding to the plurality of pixels, the plurality of pixels eachhave a first sub-pixel, a second sub-pixel, a third sub-pixel, and afourth sub-pixel, and the microlenses cause the third light to beincident on the first sub-pixels, the fourth light to be incident on thesecond sub-pixels, the fifth light to be incident on the thirdsub-pixels, and the sixth light to be incident on the fourth sub-pixels.